In the textile industry it is quite common to treat yarns with a sizing composition before they are subjected to the weaving process. In this sizing treatment the size composition adheres to and binds together filaments of the yarn thereby strengthening the yarn. A strengthened yarn is of course desirable since it is more resistant to abrasion and breaking during the subsequent weaving operation.
Many types of high molecular weight materials have been used in the past as sizing agents in the sizing of textiles. These sizing agents include, for instance, starch, starch derivatives, gelatin, polyvinyl alcohol, acrylics, alkali metal salts of maleic anhydride/styrene copolymers, and sulfonic acid metal salt derivatives of polyesters. Since most prior art sizes interfere with subsequent finishing steps they must be removed by a scouring operation before these finishing steps can be performed. Unfortunately, some of the prior art sizes are not effectively removed by scouring. Others are not readily compatible with or do not adhere well to synthetic textile yarns such as polyester yarn and thus do not form a satisfactory protective coating thereon. Yet others, while providing a removable coating, are either too expensive or impart an unsatisfactory degree of abrasion resistance.
Similarly, it is quite common in paper manufacture to size the paper either internally or externally with sizing agents to endow the paper with a number of desirable characteristics such as strength, water-repellency, ink "hold-out", (i.e. good printing qualities) and the like. Many of the paper sizes conventionally employed in these paper treating operations are not without their shortcomings. For example, a common complaint of conventional surface sizing agents is their inability to prevent "dusting" during high speed printing operations. The undesirable phenomena termed "dusting", sometimes referred to as "linting" is the result of the dust-like particles produced by the breaking off from the surface of the paper of small particulates such as protruding fibers and surface matter which have not adhered properly to the substrate. Another frequent shortcoming of conventional surface sizes is the "tackiness", however slight, that is detected in the resulting coating. Tackiness can cause paper surfaces to stick together, which is referred to in the paper trade as "blocking." Internal sizes of the prior art are frequently faulted for their inability to endow the paper with satisfactory bursting strengths.